"My notice today is for an end to my NASA employment on May 31, 2019. Due to complex nature of the efforts NASA is engaged in, I am open to discussing this situation further before that or to discussing a return to NASA in the future should the situation change. Meanwhile, I will start organizing a transition plan for the many things that I have work on and on list of outstanding activities. Please let me know who you would like me to work with on external messaging."

NASA Internal Memo: Appointment of Mark Sirangelo, 9 April 2019

"I am pleased to announce the appointment of Mr. Mark Sirangelo as a Special Assistant to the Administrator. In this role, Mark will have broad responsibility to work across the Mission Directorates to further develop the agency's plans for the Exploration Campaign. This includes a strategy to meet the Administration's policy to return astronauts to the lunar surface by 2024. He will also lead the planning for the proposed agency restructuring to create the Moons to Mars Mission Directorate that will manage the programs to develop the Gateway, human rated lander and surface ...